The subject matter discussed in the background section should not be assumed to be prior art merely as a result of its mention in the background section. Similarly, a problem mentioned in the background section or associated with the subject matter of the background section should not be assumed to have been previously recognized in the prior art. The subject matter in the background section merely represents different approaches, which in and of themselves may also be inventions.
Pattern verification, such as in a context of registration of a trusted fingerprint into a trusted memory of a fingerprint verification system, requires a sufficiently accurate and precise image of the trusted fingerprint. This image may be obtained directly from an imaging sensor. This may be suitable for large area imaging sensors. However, for many applications, the trusted image is reconstituted from images of the trusted fingerprint taken from a sensor having a sensing area smaller than the final image. For many mobile applications and electronic platforms, such as smartphones and the like, the use of the small area sensor provides a smaller form factor having a lower cost of goods which is important to implementation and adoption. However use of the smaller area sensor impacts registration and user experiences during verification.
Any mobile electronic platform having a fingerprint verification system typically includes a registration system that establishes and writes one or more trusted images into a trusted database/memory. Test fingerprints are compared against the trusted image(s) using a matching engine that matches features of interest from the test fingerprint against features of interest from the trusted image(s). A quality of the test image and of the trusted images impact the user experience.
Whatever the size of the imaging sensor, the trusted image may be derived from a single impression from a single finger, or derived from a composition of multiple impressions. Each solution offers different challenges.
It is technically possible to rely on a single impression of a single finger using a small area sensor for registration. However, during use, the user must not only recall which portion of which finger was registered, but each verification attempt relies on the user reimaging this same portion of the same finger sufficiently close that it may be matched. As the imaging sensor area becomes smaller, reliance on a single impression can become very frustrating for the user.
Many systems using a small area sensor therefore register a single finger using multiple impressions. An initial impression of an image always provides completely unique information of the larger image to be reconstituted. However, subsequent impressions have varying usefulness depending upon whether the user provides an impression that partially overlaps and partially presents new image data. The user has difficulties in placing a finger for multiple impressions to ensure only unique partial overlapping data is presented with each impression, particularly over a breadth of an entire fingerprint pattern. It is too easy for a user to provide subsequent images with too much overlap or with too little or no overlap. A user does not know when or if they have provided enough sufficiently overlapping image impressions that map enough of the total fingerprint to provide an end product that provides the user with an easy-to-use verification system.
Systems for processing images of a pattern may sometimes be desirably implemented using limited computing and memory resources. As an active area of a sensor decreases, a greater number of images are needed to cover any particular area of the pattern. Managing and processing multiple images can sometimes negatively impact performance.
Collection of a set of images of portions of a pattern for reconstruction of the pattern introduces a number of noise sources including the sensor, variations in the pattern itself, and an interaction of the sensor and the pattern. This source of noise, in turn, affects a quality of the reconstructed pattern. The reconstructed pattern may be used in a number of ways and the accuracy of those uses are often influenced by the quality of the reconstructed pattern.
A user attempting to register a specific finger (the registration relying on a reconstruction of an image of a fingerprint from the specific finger) multiple times would be extremely unlikely to reproduce 100% exact reconstructions each time. While each reconstruction has a chance, based upon a number of factors, of matching another reconstruction, a source of error in falsely rejecting a user because of a failed match increases due to the inherent variations in registering a reconstructed image and then testing the specific finger against the trusted registration image.
One way to decrease a chance of a false rejection is to register multiple reconstructed images of the same specific finger. These multiple reconstructed images of the same pattern will be different from each other and thus more likely that one will match to a user's verification attempt.
While the number of images in the set of images used to reconstruct an image varies, for a particular sensor area, resolution, pattern size, user overlap placement, and desired pattern coverage area, a finite number of images, say N number, are sampled. Conventionally, to form M number of reconstructions, M×N number of images must be collected, on average. Collecting this number of images would be considered too time consuming and unwieldly in most cases. While the conventional solution of collecting the M×N number of images likely improves performance, the solution is unlikely to be adopted as the number of impressions to be collected from the user increases.
What is needed is a system, method, and computer program product for multiplicating pattern images used as a trusted resource while reducing user participation.